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Somebody give this star a speeding ticket.

  • DaveGrennan
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15 years 9 months ago #72424 by DaveGrennan
Somebody give this star a speeding ticket. was created by DaveGrennan
Tonight I was blinking some galaxy images acquired this evening with digital sky survey references images searching for supernovae. I had a few images I ignored because some high cloud made them a bit too noisy. Anyhow when I had exhausted all the good images I went back to the grainy ones. Nothing too strange to report except;

On the very last image I noticed what looks like a star with a very high proper motion compared to other stars. Take a look at the animation below and look at the star marked on the left. Look how it changes position when compared to the DSS image. The DSS image is from the POSS-II survey which was taken over the period 1987 - 1998 so its hard to put a timestamp on that image (I'm sure I can find out). But even given the earliest date the proper motion of that star must be huge to show up so noticably. A little more research is needed methinks, but first sleep zzzzzzz.

Here's the animation;


Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
Equipment List here

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15 years 9 months ago #72425 by Vagelis Tsamis
Replied by Vagelis Tsamis on topic Re:Somebody give this star a speeding ticket.
Interesting, Dave.
Can you give us more info? What's that galaxy and FOV?

Sparta Astronomy Association / Observations Coordinator
International Occultation Timing Association / European Section, www.iota-es.de/

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15 years 9 months ago #72428 by JohnMurphy
Replied by JohnMurphy on topic Re:Somebody give this star a speeding ticket.
Could it just be an edge of field distortion?
It would be nice to get that star more central in the FOV and then do a comparison with DSS.
The weather is supposed to improve toward the end of the week - particularly Friday. See if you can duplicate the same result with fresh data and clean skies, then you may be on to something. :unsure:

Clear Skies,
John Murphy
Irish Astronomical Society
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  • DaveGrennan
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15 years 9 months ago #72435 by DaveGrennan
Replied by DaveGrennan on topic Re:Somebody give this star a speeding ticket.
Vagelis Tsamis wrote:

Interesting, Dave.
Can you give us more info?


Do the Greeks like astronomy?:laugh:

The galaxy in question is PGC 68197

Well I did lots more research on this tonight. The star in question is indeed a High Proper Motion star. The star itself resolves in Simbad as UCAC2 46198582.

Its listed in the LHS catalog of HPM stars as LHS6397. It lists as having the following PM;

PMRA 418 milliarcsec/yr
PMDEC 240 milliarcsec/yr

My own measurements seem to contradict this. I discovered (from the FITS header) the POSS plate was taken on 1989-09-04 so almost 19 years ago.

I carried out an astrometric analysis and discovered the following
DeltaA (Diff in RA) = .73"
DeltaD (Diff in Dec) = 3.68"

This thus corresponds to;

PMRA = 38.42 mas/yr
PMDEC = 193.68 mas/yr

The animation posted earlier was just a crop from the full image. Here's a better animation with the star off the edge;



This has given me a whole new idea for a little research project. To measure the proper motions of say the top 100 highest PM stars in the northern sky. Now that would be a lot of fun.

Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
Equipment List here

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15 years 9 months ago #72442 by dmcdona
Replied by dmcdona on topic Re:Somebody give this star a speeding ticket.
Nice work Dave - interesting that your calculated motion is different from LHS - certainly the DEC PM is close, but the RA PM is very different...

Definitely an eighty quid fine...

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15 years 9 months ago - 15 years 9 months ago #72446 by Vagelis Tsamis
Replied by Vagelis Tsamis on topic Re:Somebody give this star a speeding ticket.
Good job, Dave!

I also checked at Simbad and Aladin: This little beautiful star is a spectral type M 3.5 main sequense dwarf. It has a red color, as u can see at Aladin image aladin.u-strasbg.fr/alapre.pl?-c=22+09+4...1+02+05.6&button=RGB
It's amazing to see the star's energy fluxes in dif. parts of light spectrum in the Simbad page!
And it is in the "nearby stars" list.
How close is it to the Sun? I am not exactly sure which data I should look for.

Vagelis

Sparta Astronomy Association / Observations Coordinator
International Occultation Timing Association / European Section, www.iota-es.de/
Last edit: 15 years 9 months ago by Vagelis Tsamis.

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